$fn=64;

// --- PARAMETERS ---
rail_length = 600;
rail_height = 40;
rail_depth = 12;
chamfer = 8;
tolerance = 0.4; // Clearance for sliding fit

// --- MAIN ASSEMBLY ---
// Display the rail
main_rail();

// Display the modular attachments slid onto the rail
translate([80, 0, 0]) hook_module();
translate([200, 0, 0]) double_hook_module();
translate([350, 0, 0]) bin_module();

// --- MODULES ---

// 1. Base Rail Profile (used for both the rail and the cutouts)
module rail_shape(len, tol=0) {
    rotate([0, -90, 0])
    translate([0, 0, -len])
    linear_extrude(height=len)
    offset(delta=tol)
    polygon([
        [0, 0],
        [chamfer, rail_depth],
        [rail_height - chamfer, rail_depth],
        [rail_height, 0]
    ]);
}

// 2. Main Wall-Mounted Rail
module main_rail() {
    difference() {
        rail_shape(rail_length, 0);
        
        // Countersunk mounting holes every 100mm
        for(i = [50 : 100 : rail_length - 50]) {
            translate([i, 0, rail_height / 2]) {
                rotate([-90, 0, 0]) {
                    // Screw shaft
                    translate([0, 0, -1]) 
                        cylinder(h=rail_depth + 2, d=5);
                    // Countersink head
                    translate([0, 0, rail_depth - 4]) 
                        cylinder(h=5, d1=5, d2=10);
                }
            }
        }
    }
}

// 3. Single Hook Module (for leashes/collars)
module hook_module() {
    w = 40;
    difference() {
        // Base block
        cube([w, rail_depth + 6, rail_height]);
        // Sliding dovetail cutout
        translate([-1, 0, 0]) 
            rail_shape(w + 2, tolerance);
    }
    
    // Hook geometry
    translate([w / 2, rail_depth + 4, rail_height / 2 - 5]) {
        rotate([-45, 0, 0]) {
            cylinder(h=32, d=12);
            translate([0, 0, 32]) sphere(d=16);
        }
    }
}

// 4. Double Hook Module
module double_hook_module() {
    w = 80;
    difference() {
        // Base block
        cube([w, rail_depth + 6, rail_height]);
        // Sliding dovetail cutout
        translate([-1, 0, 0]) 
            rail_shape(w + 2, tolerance);
    }
    
    // Two hooks
    for(x = [20, 60]) {
        translate([x, rail_depth + 4, rail_height / 2 - 5]) {
            rotate([-45, 0, 0]) {
                cylinder(h=28, d=10);
                translate([0, 0, 28]) sphere(d=14);
            }
        }
    }
}

// 5. Bin Module (for treats or poop bag rolls)
module bin_module() {
    w = 120;
    bin_d = 60;
    bin_h = 60;
    
    difference() {
        union() {
            // Base block
            cube([w, rail_depth + 6, rail_height]);
            // Bin outer shell
            translate([0, rail_depth + 4, rail_height - bin_h]) 
                cube([w, bin_d, bin_h]);
        }
        
        // Sliding dovetail cutout
        translate([-1, 0, 0]) 
            rail_shape(w + 2, tolerance);
            
        // Hollow out the bin (4mm walls)
        translate([4, rail_depth + 8, rail_height - bin_h + 4]) 
            cube([w - 8, bin_d - 8, bin_h]);
    }
}